The present invention generally relates to tape cassettes having reel braking mechanisms, and more particularly to a tape cassette having a reel braking mechanism constructed so that in a state where the tape cassette is loaded into a recording and/or reproducing apparatus, braking against a reel is released, and in a state where the tape cassette is not loaded into the recording and/or reproducing apparatus, the unnecessary rotation of the reel is prevented by the braking operation, nevertheless the reel is rotated to pay the tape out in a case where the magnetic tape is applied with a force to be drawn out from a cassette case.
Presently, video signal recording and/or reproducing apparatuses using tape cassettes are reduced to practical use on the world-wide basis. As types of these recording and/or reproducing apparatuses using tape cassettes, two or three standardized types of apparatuses presently exist world-widely. There is no interchangeability between apparatuses of different standards, however, the interchangeability exists between apparatuses adopting the same standard. Accordingly, a tape cassette recorded by one recording and/or reproducing apparatus can be reproduced by another recording and/or reproducing apparatus of the same standard. Hence, in order to ensure the interchangeability between different recording and/or reproducing apparatuses manufactured by different manufacturers so as to perform recording and/or reproduction, a standardization is established with respect to formats of the tape cassette and the recording and/or reproducing apparatus. That is, the above formats are standardized for each standard, and a standard type tape cassette and a standard type recording and/or reproducing apparatus are respectively manufactured and marketed under each standard.
Recently, a problem of much importance involves the realization in reducing the size of the recording and/or reproducing apparatus main body. This is to realize a more compact portable type recording and/or reproducing apparatus, and, for example, to realize such an equipment that a recording apparatus is unitarily built into a television camera.
In this regard, some attempts have been made to realize a compact type recording and/or reproducing apparatus using a compact or miniature type tape cassette, which uses a tape pattern and format completely different from those of the standard type recording and/or reproducing apparatus using the standard type tape cassette which are already and widely accepted in the market. However, the above compact type recording and/or reproducing apparatus attempted for realization uses a format completely different from that of the standard type recording and/or reproducing apparatus, and the interchangeability does not exist therebetween. Therefore, in this compact type recording and/or reproducing apparatus, there is a disadvantage in that a tape cassette recorded by the compact type recording and/or reproducing apparatus cannot be reproduced by the standard type recording and/or reproducing apparatus. This is a great inconvenience and disadvantage to the owners of the compact type recording and/or reproducing apparatus.
Another attempt has also been made to realize a compact type portable recording and/or reproducing apparatus which performs recording and/or reproduction with the same tape pattern and format as the standard type recording and/or reproducing apparatus, by using a tape cassette whose size is slightly reduced by reducing the tape quantity and the diameter of the reels from those of the standard type tape cassette. In this system, a tape cassette recorded by the portable recording and/or reproducing apparatus can be reproduced as it is by the standard type recording and/or reproducing apparatus.
However, in the tape cassette used in the above portable recording and/or reproducing apparatus, the distance between a supply reel and a take-up reel is set equal to the distance between the supply and take-up reels of the standard type tape cassette, so that the tape cassette used for the portable recording and/or reproducing apparatus can be loaded into the standard type recording and/or reproducing apparatus. Hence, even when the tape quantity is reduced in order to reduce the diameter of the reels, there is a limit in reducing the diameter of these reels. Therefore, in this system, there was a disadvantage in that the size of the tape cassette as a whole could not be reduced significantly, and the same is true to the recording and/or reproducing apparatus.
Furthermore, another system is conceivable in which the tape quantity is reduced to reduce the diameter of the reels, and further, the miniature type tape cassette is constructed by reducing the distance between the supply and take-up reels. In this system, as a modification of the standard type recording and/or reproducing apparatus, the recording and/or reproducing apparatus can be constructed so that a reel disc for driving the take-up reel is movable. In this modification of the standard type recording and/or reproducing apparatus, the take-up reel disc is at a normal position when loaded with the standard type tape cassette, and the take-up reel disc is moved to a position closer to the supply reel disc when loaded with the miniature type tape cassette.
However, even in this system, for example, there is a disadvantage in that the miniature type tape cassette recorded by the compact type recording and/or reproducing apparatus cannot be reproduced by the standard type recording and/or reproducing apparatus which is presently in wide use. Moreover, there is a disadvantage in that it is extremely difficult to realize a mechanism for moving the reel disc in the manner described above. Furthermore, the recording and/or reproducing apparatus using the tape cassette generally has a mechanism for drawing out the tape from inside the tape cassette to load the tape onto a predetermined tape path within the recording and/or reproducing apparatus. Therefore, it is also exceedingly difficult to construct the above mechanism for pulling out the tape, so that interchangeability exists with respect to the above compact or miniature type tape cassette and the standard type tape cassette. Practically, the realization of such a mechanism is virtually impossible.
Accordingly, in a U.S. patent application Ser. No. 322,174 filed on Nov. 17, 1981 entitled "TAPE CASSETTE", in which the assignee is the same as that of the present application, a novel and useful tape cassette which has overcome the above described disadvantages was proposed, and this novel tape cassette is now being realized.
In the above previously proposed tape cassette, a braking mechanism is provided to prevent unnecessary rotation of the reels. This mechanism is provided so that the supply reel and the take-up reel within the cassette case do not rotate unnecessarily when the tape cassette is not used. Accordingly, slack is prevented from being introduced in the tape, and the tape is prevented from being excessively exposed outside the cassette case. To be more concrete, a braking mechanism is provided with respect to the take-up reel so that when the tape cassette is not used, braking is performed with respect to the peripheral edge of a reel flange so that the take-up reel does not rotate, and when the tape cassette is loaded into a tape cassette adapter or a recording and/or reproducing apparatus, the above braking is released. In addition, with respect to the supply reel, a braking mechanism is provided wherein teeth are provided in a ring shape on the lower surface of a reel flange, teeth are provided in a ring shape on a bottom plate of the cassette case at positions corresponding to the teeth formed on the lower surface of the reel flange, and a spring is provided to urge the supply reel downwards. In the braking mechanism provided with respect to the supply reel, the teeth of the reel flange of the supply reel which is urged downwards, mesh with the teeth provided on the bottom plate of the cassette case, to prevent unnecessary rotation of the reel. When the tape cassette is loaded into the recording and/or reproducing apparatus directly, or in a state accommodated within the adapter, a reel driving shaft of the apparatus enters into a center hole of the supply reel to lift up the supply reel. Hence, in this case, the above teeth are disengaged from the meshed state, and the braking with respect to the supply reel is released.
In the above teeth formed on the reel flange and formed on the bottom plate of the cassette case, the convex part and the concave part of the tooth have a rectangular shape. Thus, in a state where the tape cassette is not loaded into the recording and/or reproducing apparatus, the crest part and the valley part of both teeth perfectly mesh, permitting almost no rotation of the supply reel. Therefore, when the tape cassette is not used, the supply reel is essentially prevented from rotating unnecessarily.
On the other hand, when the tape cassette is accommodated within the adapter, it is necessary to draw a portion of the tape out of the cassette case, to form a predetermined tape path within the adapter. In this case, the operator inserts a finger of his one hand from the lower part of the cassette case to lift the supply reel and release the engagement of the teeth. But while maintaining this state, the operator must draw the tape outside the cassette case with fingers of his other hand. The tape cassette is thus loaded into a predetermined position within the adapter, while the tape thus drawn out is guided along the predetermined tape path within the adapter. However, in this case, there was a disadvantage in that the operation to lift the above supply reel with the finger to release the engagement between the teeth and release the braking operation, was troublesome to perform.
Furthermore, an adapter has been proposed having a construction such that the tape cassette is loaded as it is into the adapter, and a lever provided in the adapter is angularly rotated to draw the tape outside the cassette case and guide the tape along the predetermined tape path within the adapter. When the tape cassette is loaded into the adapter, a pin provided on the adapter relatively enters within the cassette case, to release the braking against the take-up reel. Accordingly, although the braking against the supply reel maintained when the lever in the above adapter is angularly rotated, the tape can be drawn out from the take-up reel to be guided along the predetermined tape path since the take-up reel is released of the braking and can rotate. However, in a case where all the tape is wound onto the supply reel of the tape cassette which is loaded into the adapter, and there is no tape or leader tape wound around the take-up reel to allow the tape to be drawn out from the take-up reel, a problem is introduced. That is, an excess force is applied to the tape when the lever in the adapter is angularly rotated. In extreme cases, the tape will be broken because of this excessive force applied to the tape.